Here are some nice explanations of the most common java exceptions like:

ConcurrentModificationException= Someone else has modified your Java code. You should probably change your password.IndexOutOfBoundsException =Â You have put your index finger in an unacceptable place. Reposition it and try again.RuntimeException= You cannot run fast enough, possibly due to obesity. Turn off your computer and go out and get som exercise.NumberFormatException =Â You are using outdated units of measurement, for example inches or pints. Convert to SI. There is a known bug that causes this exception to be thrown if you are very short or tall.